Yesterday I was playing a League match against SamE and twice the game ended up freezing during my turn, I couldn't buy, play cards, or pass my turn. I tried changing Computer and Browser and the game continued in it's stuck state. Another League game of Aku Chi vs Mic Qsenoch was played around the same time and it seems like they found a work around involving asking for an undo. Unfortunately i did not think about doing that, but luckily both games were close enough to being over that there was really not much harm done.
Game numbers were
Both endgame states are saved as of the moment the freezing occurred, just after buying Inheritance in the first one, and after King's Courting a Smithy in the second one, in the second game my opponent could see that the game was frozen because the log said I played Smithy but never got to draw the cards.
I took a screenshot, but there is a video of Aku Chi vs Mic Qsenoch match where the problem is clearly visible (and much better to visualize what happened). What happened to me is exactly alike what happened to Aku Chi in the following video at the 1:11:42 mark. And they mention in chat that it had already happened previously.https://www.youtube.com/watch?v=fzEfdZXrOFs